Lifting Symplectomorphism Group Actions on Bi-Lagrangian Structures to the Whitney Sum

Abstract

Let $M$ be a manifold endowed with a bi-Lagrangian structure $(ω,\mathcal{F}_{1},\mathcal{F}_{2})$. Thus, $ω$ is a symplectic form, and $(\mathcal{F}_{1},\mathcal{F}_{2})$ is a pair of transverse Lagrangian foliations on the symplectic manifold $(M,ω)$. We prove that, if $M$ is parallelizable, then every bi-Lagrangian structure on $M$ naturally induces bi-Lagrangian structures on the tangent bundle $TM$ and on the cotangent bundle $T^*M$, and hence on the Whitney sum $W = TM \oplus T^*M$. We show that, if the bi-Lagrangian structures of $M$ can be lifted to $TM$ or $T^*M$, then the action of the symplectomorphism group on the set of bi-Lagrangian structures defined in \cite{TNB} admits natural lifts to $TM$, $T^*M$, and hence to $W = TM \oplus T^*M$.